We plan to continue our investigation of the renal handling of cadmium-metallothionein (Cd-MT) in the rabbit; attention will focus specifically on the mechanisms of Cd-MT reabsorption. Demonstration of a saturable mechanism involved in this reabsorption suggests that Cd-MT may interact with the brush border membrane. We propose to study this interaction in vivo by determination of tubular transmit kinetics at varying Cd-MT concentrations, and in vitro by measurement of Cd-MT binding to isolated brush border fragments. Results of such work may have significant bearing on the general question of protein reabsorption. At the same time we plan to continue exploration of the isolated renal glycinuria which we observed in a group of rabbits exposed to Cd in their drinking water. This will require careful control of diet, and especially, mineral nutrition of these animals. BIBLIOGRAPHIC REFERENCE: Foulkes, E.C. and Johnson, D.R. Isolated renal glycinuria in rabbits exposed to Cd. Fed. Proc. 36:1618, 1977 (Abstract).